Mercury, as a kind of toxic heavy metal, may injure nervous system, brain tissue and liver tissue after entering into the human body, and can accumulate in living creature and transfer around the world along with the food chain, thus having great harms. About one third of mercury discharged into the atmosphere comes from the mixed combustion process of coal or coal and wastes and the environmental protection pressure in China is tremendous because of the huge consumption of coal.
Considering that most power plants are now equipped with selective catalytic reduction (SCR) denitration devices and wet desulfurization systems, there is no need to add independent mercury removal equipment by oxidizing zero-valent mercury into bivalent mercury and then removing mercury in desulfurization system, which will help power plants to save pollutant control cost and have greater application prospect. However, low-chlorine coal is mainly used in power plants in China with lower HCl concentration in flue gas, while the current commercial SCR catalyst has a low mercury oxidation efficiency, which restricts the control of mercury in coal-fired power plants especially under the condition of low chlorine.
A Chinese patent CN102764655A discloses a new mercury removal catalyst which is prepared via pillared montmorillonite by mixing TOx (T refers to Cu, Fe, V) and ROy (R refers to La, Ce) with titanium dioxide. Such catalyst has high mercury removal efficiency, a certain anti-poisoning ability, no denitration capability and a complicated preparation process, and thus is not applicable for industrial application.